<!DOCTYPE html>
<html>

<head>
    <style>
        h1 {
            text-shadow: 20px 20px 5px blue;
        }

        h1:hover {
            overflow: visible;
        }
    </style>
</head>

<body>

    
    <h1>文本阴影效果！</h1>

</body>

</html>